DG quality?

Interesting that "bumper" considered crash resistance in his
choice between DG800 and ASH26E. If surviving an accident is
the sort of thing that worries you remember that only DG offer
the NOAH pilot ejection system. I had one in a DG808C and
don't have one in my current motor glider: I miss it.
If you're of a more philosophic nature a bigger question might
be the relative merits of the engines in the 800/26E.
If you're a purist without an engine I'd stop worrying about DG
quality, it's fine, the finish/gel coat being notably long lasting.
In addition dealing with the DG company for spares,
information, etc was a joy - fast, efficient, reliable; never had a
problem in 10+ years.

My experience as customer of Schempp, as a part owner of a
Duo, was less wonderful.

Never owned a plastic Schleicher so can't help there.